Chairmen of the House Intelligence and Senate Judiciary committees have run out of patience with the Department of Justice as their requests for documents have met with repeated delays, denials, and pushback.

Senator Charles Grassley has waited for more than 16 months to receive documents concerning the FBI’s interview of Michael Flynn, the former national security advisor to President Donald Trump. The senator’s June 6 letter to Deputy Attorney General Rod Rosenstein breaches cordiality to castigate the department as being “disingenuous and extremely disturbing” for pushing back on Grassley’s request to interview a witness.

Meanwhile, Representative Devin Nunes has given the Justice Department until Tuesday, June 12, to produce the documents he has demanded for over a year and issued a subpoena for April 30. The information Nunes is seeking relates, at least in part, to the FBI’s use of a spy to infiltrate the Trump campaign. Similar to Grassley, Nunes’ letter to Rosenstein betrays anger about the continued pushback.

“DOJ continues to obfuscate and delay its production using an array of tactics, such as incorrectly categorizing the requested documents as Gang-of-Eight-level material in order to limit access,” Nunes wrote in a letter sent to Rosenstein on Friday. “Such conduct by DOJ is unacceptable because the Gang-of-Eight is a legal fiction that has no basis outside of the confines of Presidential approval and reporting of covert actions.”

“Your continued refusal to permit Members of Congress and designated staff to review the requested documents is obstruction of a lawful Congressional investigation,” Nunes added.

The irritation displayed by Nunes and Grassley, who chair the House Intelligence and Senate Judiciary committees respectively, comes days before the release of a report by the Justice Department inspector general that is expected to include severe criticism of several former top Justice Department officials, including former FBI Director James Comey and former Attorney General Loretta Lynch.

The chairmen’s recent requests follow nearly a year of congressional investigations that unearthed a barrage of evidence that FBI officials may have abused their authority to spy on the Trump campaign and damage his administration after the inauguration.

Grassley Presses On

For more than a year, Grassley has been demanding to view a transcript of Flynn’s call with Russian Ambassador Sergei Kislyak as well the field notes taken by the FBI agents who interviewed the former national security advisor about the call. Flynn resigned from the Trump administration in February last year and pleaded guilty to lying to the FBI in December.

Flynn’s indictment and guilty plea cast a spotlight on Comey’s testimony before Grassley’s committee. Six months before the indictment, Comey told lawmakers that the FBI agents who interviewed Flynn did not think he was lying. According to Grassley, an FBI agent who was present during Comey’s testimony took notes corroborating what the committee members recall.

Comey would go on to deny having told the committee that agents did not think Flynn was lying. To get to the bottom of the contradiction, Grassley demanded the agents’ notes, known as 302s.

The FBI has used the ongoing court case against Flynn as the reason to not release the documents to Grassley. When Flynn pleaded guilty, Grassley informed the DOJ that there is was no reason to continue withholding the documents.

According to Paul Sperry, a Hoover Institution media fellow, Senate investigators suspect that former FBI Deputy Director Andrew McCabe edited the 302s. The investigators sent a referral to the Justice Department’s Inspector General Michael Horowitz to investigate the matter. Grassley’s office did not respond to a request to confirm the referral.

This is not the first time that Grassley’s committee discovered evidence that contradicts the FBI’s 302 reports. In January, Grassley gave a speech revealing that his committee’s oversight investigation has discovered 302s that contradicted sworn testimony from Christopher Steele, the former British spy who compiled the infamous anti-Trump dossier.

“In the course of our review, Senator Graham and I came across some information that just does not add up,” Grassley said. “We saw Mr. Steele swearing one thing in a public libel suit against him in London. Then we saw contradictory things in [FBI] documents that I am not going to talk about in an open setting. And from everything we’ve learned so far, we believe these discrepancies are significant.”

The FBI used Steele’s dossier as the core evidence to secure a warrant to spy on Trump campaign volunteer Carter Page. According to the FBI, the officials involved in applying for the warrant did not know that Steele had been shopping his dossier to the media. But Steele, in a court filing for his libel suit in the United Kingdom, said that he shopped the dossier around at the behest of his client, Fusion GPS.

To ferret out the truth behind the discrepancy, Grassley demanded in January that the Department of Justice charge Steele for lying to investigators. The department did not file charges.

Nunes Undeterred

Nunes has likewise not relented despite incessant pushback from the Justice Department. His House Intelligence Committee released a bombshell report last year exposing a pattern of problematic steps taken by senior officials in their investigation of the Trump campaign’s alleged ties to Russia.

The committee’s work did not stop after the report’s release. Evidence has surfaced since that the FBI probe of the Trump campaign started earlier than the agency has previously claimed. Anonymous leaks revealed that an FBI spy had infiltrated the Trump campaign prior to the start of the investigation.

That revelation is problematic since the agency would need to come up with a new explanation for why it started investigating the Trump campaign. The FBI’s current reason for starting the probe is a drunken rant by former Trump campaign volunteer Carter Page to a top Australian diplomat in London. Page mentioned that Russia has dirt on Hillary Clinton.

Nunes’s current request for documents is in the form of a classified letter. The details are not public, but it likely concerns the spy and the reasons for the start of the investigation.

The Justice Department responded to the intelligence committee’s most recent request by offering to brief the Gang of Eight on the related documents on Thursday. The Gang of Eight consists of the leaders of both parties in the House and Senate, as well as the heads of the intelligence committees in both chambers. Nunes was not satisfied with the offer and demanded that the documents be made available to all the committee members and designated staff.

House Permanent Select Committee on Intelligence Chairman Devin Nunes (R-Calif.) speaks to reporters during a press conference at the U.S. Capitol in Washington on March 22, 2017. (Win McNamee/Getty Images)

The Justice Department has so far held two meetings to brief a select group of lawmakers on the contents of the documents that Nunes is requesting. House Speaker Paul Ryan was one of the officials briefed but is backing Nunes’s request of actual documents.

“We received an oral briefing two weeks ago. But what we are asking for, and what we require and we expect, is the corroborating documents that back up that oral briefing,” Ryan said at a press conference last week.

“So it is our job to conduct oversight,” Ryan added. “So, that is why you’ve seen frustration—frustration by me, frustration by Chairman Nunes, frustration by a lot of our members—that the foot-dragging by the Department of Justice should not be tolerated.”

Nunes has already threatened to start impeachment proceedings against Rosenstein if the deputy attorney general continues withholding the documents. He concluded his letter signaling that further resistance would be interpreted as an attempt to conceal evidence from Congress.

“I will not relent in my duties on behalf of the American public to discover all the facts in this matter,” Nunes wrote. “Any response falling short of this request will be considered an effort to conceal material information from Congress—a dangerous precedent that threatens the core of our democracy.”